WE cruised around South America last February and absolutely froze on a walking tour of the Falklands and even on a bus tour in Ushuai. We almost died of the heat in Valpraiso, our point of departure and again in Argentina. We chose to take the ship tours because we were visiting ports we'd probably never see again. Table mates who spoke not a single word of Spanish were quite happy with their taxi tours, though they didn't learn much.
We're from Canada and even our gloves and gortex jackets were not enough for the Falklands. We encountered rough seas -- 45 feet waves as we neared the Str. of Magellan. The pools were frequently netted as the decks were blocked. My advice -- prepare for heat and cold. Ship dress was more tropical than winter for sure. A ship full of optimists.
We were fortunate to have a two week travel adventure on our own pre cruise and another week and a bit post cruise. Of the entire 6 week trip the best part was our time in Peru. My husband has decade old university Spanish so we managed quite well and probably could have done the taxi bit on our own.